This sort of infrared sensor switch is installed on, for example, a ceiling, a wall or the like to be utilized as an energy-saving unit. For example, a terminal unit described in Japanese Patent Application Publication No. H6-245282 issued Sep. 2, 1994 is installed on a wall. This unit comprises a printed circuit board on which an infrared sensor is mounted, and a rotating frame that retains the board and is rotated about a vertical axis through a direction adjusting knob. In case of this unit, an axis toward a center of a detection range of the infrared sensor can be rotated about the vertical axis. However, since the positions of the top and bottom ends of the detection range are not changed, a human body cannot be detected in case that the unit is installed at a high place on a wall.
An infrared sensor switch described in Japanese Patent Application Publication No. H4-55728 issued Feb. 24, 1992 is installed on an outdoor wall. This switch comprises a sensor block that includes an infrared sensor (pyroelectric element) and is rotated about a horizontal axis. In case of this switch, since the axis toward the center of a detection range of the infrared sensor can be rotated about the horizontal axis, the positions of the top and bottom ends of the detection range can be changed. However, the axis toward the center of the detection range is rotated up and down from 45 degrees below but the axis cannot be directed to the forward direction, and therefore a human body may not be detected in case that the switch is installed at a lower position than a person.